U.S. Pat. No. 4,912,011 discloses a light-sensitive material comprising a support and a light-sensitive layer provided thereon which contains silver halide, a reducing agent, a polymerizable compound and a color image forming substance. The silver halide, the reducing agent, the polymerizable compound and the color image forming substance are contained in microcapsules (light-sensitive microcapsules) which are dispersed in the light-sensitive layer. The U.S. Patent corresponds to Japanese Patent Provisional Publications No. 61(1986) 275742 and No. 61(1986)-849 and European Patent Provisional Publication No. 0203613A.
An image forming method using the light-sensitive material is also disclosed in U.S. Patent 4,912,011. The method comprises the steps of imagewise exposing the light-sensitive material, and heating the light-sensitive material. A latent image of the silver halide is formed by the exposure. The polymerizable compound is polymerized by heating within the area where the latent image has been formed. The light-sensitive material is then pressed on an image-receiving material to transfer the unpolymerized polymerizable compound with a color image forming substance to the image-receiving material to form a color image on the image-receiving material.
Further, a method of polymerizing the polymerizable compound within the area where the latent image of the silver halide has not been formed is disclosed in Japanese Patent Provisional Publications No. 61(1986)-243449, No. 61(1986)-260241, No. 2(1990)-141756 and No. 2(1990) 141757. The contents of the former two publications are described in European Patent Provisional Publication No. 0202490A.
On the other hand, U.S. Pat. Nos. 4,440,846, 4,483,912 and 4,554,235 disclose a light-sensitive material comprising a support and a light-sensitive layer provided thereon which contains a photopolymerization initiator, a polymerizable compound and a color image forming substance. The photopolymerization initiator, the polymerizable compound and the color image forming substance are contained in microcapsules (light-sensitive microcapsules) which are dispersed in the light-sensitive layer. U.S. Pat. No. 4,440,846 corresponds to Japanese Patent Provisional Publications No. 57(1982).179836, No. 58(1983) 88739 and No. 58(1983).88740. U.S. Pat. No. 4,483,912 corresponds to Japanese Patent Provisional Publications No. 59(1984)-30537 and No. 59(1984)-137944. U.S. Pat. No. 4,554,235 corresponds to Japanese Patent Provisional Publication No. 60(1985)-259490.
An image forming method using the photopolymerization initiator comprises imagewise exposing the light-sensitive material to imagewise polymerize the polymerizable compound by the photopolymerization initiator. The light-sensitive material is then pressed on an image-receiving material to transfer the unpolymerized polymerizable compound with a color image forming substance to the image-receiving material to form a color image on the image-receiving material.
The above-mentioned light-sensitive materials are prepared by a process comprising the steps of: (I) mixing a silver halide emulsion and a reducing agent (U.S. Pat. No. 4,912,011 et al.) or a photopolymerization initiator (U.S. Pat. No. 4,440,846 et al.) with a polymerizable compound to prepare a light-sensitive composition; (II) emulsifying the composition in an aqueous medium to prepare an aqueous emulsion; (III) forming a shell around the droplets of the composition contained in the aqueous emulsion to prepare a microcapsule dispersion; (IV) preparing a coating solution of the light-sensitive layer from the microcapsule dispersion and (V) coating the solution on a support.
FIGS. 3A and 3B are flowcharts schematically illustrating the conventional process for preparation of the light-sensitive material containing silver halide and a reducing agent. The light-sensitive material shown in FIG. 3A is a preferred embodiment wherein a color image forming substance and a base precursor in addition to the silver halide, the reducing agent and the polymerizable compound are contained in microcapsules. The light-sensitive material shown in FIG. 3B also is a preferred embodiment which forms a color image by using blue, green and red sensitive microcapsules.
At the step (I), a color image forming substance (32), a solution of a reducing agent (33), a dispersion of a base precursor (34) and a silver emulsion (35) are mixed with a polymerizable compound (31) to prepare a light-sensitive composition (36). At the step (II), the light-sensitive composition (36) is emulsified in an aqueous medium (37) to prepare an aqueous emulsion (38). At the step (III), a shell is formed around the droplets of the composition contained in the aqueous emulsion (38) to prepare a microcapsule dispersion (39). At the step (IV), a blue sensitive microcapsule dispersion (41), a green sensitive microcapsule dispersion (42) and a red sensitive microcapsule dispersion (43) are mixed to prepare a coating solution of the light-sensitive layer (44). At the step (V), the coating solution (44) is coated on a support (45) to prepare a light-sensitive material (46).
The above-mentioned light-sensitive materials can be used for various technical fields such as color photography, printing and copying (e.g., a computer-graphic hard copy and a color copy). Accordingly, various kinds of the light-sensitive material are required in practical use. The difference practical uses require different light-sensitive materials, particularly with respect to spectral sensitivity and hue of the formed color.